DESCRIPTION(provided by applicant): Placental abruption places a tremendous health burden on both the mother and the newborn, and efforts to understand the underpinnings of this devastating obstetrical complication hav been disappointing. This project will delineate pathways to abruption and determine th impact of air pollutant triggers that are implicated in acute versus chronic abruptions Given that a fourth of all abruption cases have an acute etiology, the role of environental triggers is a critically important, yet unexplored, opportunity to understand the pahophysiology of abruption. The project will capitalize on hospital discharge data linked to both stillbirths and live birth-infant deaths to resident mothers in New York City. These daa, with geocoded residence information, include an estimated 840,000 births (about 7,000 abruption cases of which 4,810 will be severe cases to New York City residents during the period 2008-14. For each pregnancy, we will assign ambient exposure to fine particulate matter with n aerodynamic diameter <2.5 M (PM2.5), its constituents (nickel, zinc, and iron), blak carbon (BC) and gaseous pollutants including nitrogen dioxide (NO2), ozone (O3), and sulfur dioxide (SO2) based on residential address and gestational age at the time of the exposure. The analyses will focus on disentangling the relative contributions of these air pollutants on acute abruption cases through a case- crossover design and those of abruptions with chronic underpinnings using a cohort design. We will apply generalized linear mixed models integrated with the Bayesian adjustment for confounding. Given the ubiquitious nature of the air pollutants and their potential impact of adverse perinatal outcomes, and virtually no data on placental abruption, the proposed project represents a unique opportunity to make discoveries that will improve maternal and infant health and guide public health policy.